correct dockerfile entrypoint for artifactsd

rebuild docker image when build-artifacts.sh changes

external-libs/build/Makefile

@@ -64,7 +64,8 @@ artifactsd: distfiles
 	  -v $(shell pwd)/artifacts-verification:/var/src/artifacts-verification \
 	  -v $(shell pwd)/distfiles:/var/src/distfiles \
 	  -v $(shell pwd)/build-artifacts.sh:/usr/local/bin/build-artifacts.sh \
-	  xmrwallet_build /bin/bash
+	  --entrypoint /bin/bash \
+	  xmrwallet_build
 
 artifacts-verification: distfiles artifacts/packages.checksum
 	@echo "running a verification build that compares with a previous artifacts build"
@@ -82,6 +83,6 @@ artifacts-verification: distfiles artifacts/packages.checksum
 	  xmrwallet_build /bin/bash /usr/local/bin/build-artifacts.sh \
 	    verify
 
-.docker_image:
+.docker_image: build-artifacts.sh
 	docker build . -t xmrwallet_build
 	touch .docker_image